Batteries convert stored chemical energy into electrical energy and are commonly used as energy sources. Typically, a battery comprises one or more electrochemical cells including a negative electrode, a positive electrode, an electrolyte, and a battery separator. A battery separator is a critical component in many batteries. The battery separator mechanically and electrically isolates the negative and positive electrodes, while also allowing ions in the electrolyte to move between the electrodes.
Battery separators should be chemically, mechanically, and electrochemically stable under the strongly reactive environments in the battery during operation, should not adversely interact with the electrolyte and/or electrode materials, and have no deleterious effect on the battery's performance (e.g., energy production, cycle life, safety). For example, the battery separator should not degrade, leach harmful components, react in a negative way with the electrode materials, allow short circuits to form between the electrodes, and/or crack or break during battery assembly and/or operation. Batteries separators also play a role in determining the assembly speed of the battery, as well as the performance during service. For example, during assembly, acid electrolyte may be filled into the battery containers and the structure of the separator can impact the speed of the filling and distribution of the electrolyte within the battery (e.g., stratification). Though many battery separators exist, improvements in the retention of electrolyte, and/or improvements in formation of the battery, would be beneficial.